The -03 year will involve characterization of the PNF surfaces as a function of radiation crosslinking. This will be done by measuring heats of adsorption microcalorimetrically, by dielectric measurements and by critical surface tension and/or contact angle studies, involving techniques which we have developed as part of this grant. The heat of adsorption studies will attempt to determine the variation of strength of protein bonding with the surfaces vs. radiation as well as differences in the extent of denaturation or ordering of the adsorbed proteins on the surface. The dielectric studies will attempt to elucidate differences in molecular mobility on the surface and in the bulk vs. radiation crosslinking. It is anticipated that these experiments will enable us to differentiate between the surface and bulk properties of the PNF's and the effect of each on thrombogenesis.